Method of and device for the manufacturing of electrical conductors

ABSTRACT

A method of and device for manufacturing electrical conductors, in which individual metal wires are assembled to form a strand in a first process phase, the wire strand being subsequently twisted in a second, separate process phase. During this second phase, the strand is fed from a driven spool into a rotating container and is subjected to a first twist. Subsequently, with an unchanged direction of rotation, the direction of movement of the strand is reversed, and the strand is rewound onto the spool, the strand thus being subjected to a second twist. The device for performing this method comprises a drive for a spool, a rotating container with a wire guide, and a winding mechanism with a synchronizing unit.

United States Patent 1191 11 1 ,851,454 7 Beyer et al. Dec. 3, 1974 METHOD OF AND DEVICE FOR THE 3,096,610 7/1963 Bunch 57/5852 x MANUFACTURING OF ELECTRICAL g; H

- arvey CONDUCTORS 3,635,007 1/1972 Yoshida et a1 57/166 X [75] Inventors; Jeno Beyer, Delft; Leonardus 3,643,411 2/1972 Vogelsberg 57/5852 X Eduard Govaert, Venlo, both of Netherlands Primary Examiner-Donald E. Watkins 73 Assignee: us. Philips Corporation, New Mame) Agem York, N.Y. 5 CT 7 [22] Filed: Sept. 7, 1973 1 TRA A method of and device for manufacturing electrical 1 PP ,018 conductors, in which individual metal wires are assembled to form a strand in a first process phase, the wire [30] Foreign Application Priority Data strand being subsequently twisted in a second, sepa- S t 30 1972 N h l 7213274 rate process phase. During this second phase, the ep ct er an strand is fed from a driven spool into a rotating container and is subjected to a first twist. Subsequently, 8 with an unchanged direction of rotation, the direction of movement of the strand is reversed, and the strand [58] Field of Search 57/5852 34 is rewound onto the spool, the strand thus being sub- 62 jected to a second twist. The device for performing this method comprises a drive for a spool, a rotating [56] References Clted container with a wire guide, and a winding mechanism UNITED STATES PATENTS with a synchronizing unit. 2,431,617 11/1947 Martinez 57/34 CF 2,998,694 9 1961 Haugwitz 57/5852 6 m 7 Drawmg Flgures SHEU 2 BF 3 PATENIEL EEC 3:914

m N g METHOD OF AND DEVICE Eon THE MANUFACTURING or ELECTRICAL CONDUCTORS .The invention relates to a method of and a device for manufacturing electrical conductors, in which a number of individual metal wires are unwound from-spools, are assembled to form a strand which is fed to a twisting device, said strand being twisted while passing through the twisting device, and the electrical conductor thus obtained is wound onto a spool.

In known methods of this kind the individual wires are unwound from the feed spools (driven or not driven) and are directly fed to a twisting device. The maximum unwinding speed of the wires is then limited by the twisting speed. During the unwinding of the comparatively'large number of wires, the risk of disturbances is much higher than during twisting. A disturbance in the unwinding of the wires such as caused, for example, by the breaking of one of the wires, results in an interruption of the entire process. The wire is sub jectto high and irregular stresses which have an adverse effect on the quality of the electrical conductor;

This object is-achieved according to the invention mainly in that the individual metal wires are first bun dled to'form a strand in a first process phase on an doubling machine andare; wound onto a'spool, the spool with the wire strand being subsequently/introduced into a separate twistin'g device, the strand being twisted in a second, separate process phase.

By sub-dividing the process into two. phases, each phase can perform at a higher speed and with a higher optimum efficiency. Any disturbance in the unwinding of the wires will occur during the assembly phase, so it will not cause a disturbance of the twisting processThe tensile forces developed during the unwinding of the wires have no adverse effect on'the" twisting process. The process, can be performed andsupervised by a smaller number of operators. The bundling of the wires can be effected by knowntechniques. The wires are bundled by doublingrin order. to keepthe comparatively large number of wirestogether, the wire strand is preferably slightly pre-twisted with a pitch in the order of l m. g t

It is to be noted that in textile technology it is known per se to double and twist yarn in separate operations. However, less heavy spools are used and also a substan tially smaller number of threads, with the result that the yarn stressesoccurring are much smaller, so that the risk of disturbances is also much smaller. I 1 t In a preferred embodiment of themethod according to the invention, the wire strand is unwound fromthe driven spool in the twisting device, is fed into a rotating container and deposited regularly along theinner wall thereof with the result that the strand is subjected to a first twist. The direction of movement of the wire strand is subsequently'r'eversed while the direction of rotation of the container is maintained, the strand being then withdrawn from the container and rewound onto the same spool, with the result that the strand is subjected to a second twist.

The centrifugal twisting whereby yarn is deposited on the inner wall of a rotating container is already known from the textile technique. The present invention enables the use of the principle of the centrifugal twisting process in the metal industry for the twisting of nonelastic metal wire; in a first twisting phase, the metal wire is pro-shaped and in a second twisting phase it is twisted at the desired pitch and to the definite length. By subdividing the twisting process into two phases, it being possible to vary the twisting effect in both phases, the twisting process can be performed in a controlled manner. With the method according to the invention, the twisting takes place axially in the axis of a rotary generator; in contrast with the twisting process known in the metal industry, the centrifugal twisting process according to the invention causes little noise; this is an important factor in view of the increasingly severe requirements which are imposed so as to protect the operating personnel against excessive noise.

Due to the use of already bundled wire according to the invention, by driving the feed spool and by the rotation of the pot, a first twist is imparted to the strand, the individual wires being exposed to only a comparatively small constant tensile force. By reversing the direction has been unwound from the spool, with the exception of a given length. However, the direction of rotation of the spool preferably remains unchanged; if the beginning end of the strand is secured to the spool core before doubling, the reversal of the direction of movement of the wire is readily obtained by the unchanged and uninterrupted rotary movement of the spool.

In another preferred embodiment of the method according to the invention, the tension of the wires is minimized during the emptying of the container by withdrawing the strand from the instantaneous take-off point on the container wall to'the axis of the container, substantially in a plane which is perpendicular to said axis. It is thus achieved that also during the rewinding I only a slight and substantially constant tensile'force.

This embodiment is preferably used in the manufacture of very sensitive products which are subject to very severe requirements as regards the tolerances of the wire tension.

The device for performing the method according to the invention is characterized in that it comprises a bearing for a rotatable spool, a drive unit for the spool, a rotatable container, a drive unit for the container, a traversing wire guide which determines the winding structure in the container, and a winding mechanism with a driven unit associated with the spool.

The device has a comparatively simple construction, is compact, and can be simply operated. The known devices for manufacturing electrical conductors operate according to the balloon principle, in which the rotating wires and heavy rotating machine parts require much energy and cause much noise. In contrast therewith, the device according to the invention operates according to the container principle in which, as already explained, the twisting takes place in an axial twisting process in the axis of the container which acts as a rotary generator; as a result, this process produces very little noise, whilst the maximum speed and the efficiency are very high.

A preferred embodiment of the device according to the invention is characterized in that it comprises a switching bar which can be displaced by the wire strand and which cooperates with switches for switching on the winding mechanism and for reversing the direction of movement of the wire guide upon reversal of the direction of movement of the strand.

As a result, the reversal of the direction of movement of the wire can be automatically effected, without interruption of the twisting process.

In order to enable the withdrawing of the strand during the emptying of the container from the instantaneous take-off point to the axis of the container in a plane perpendicular to said axis, the traversing movement of the wire guide must be synchronous with the take-off point on the container wall. To this end, a further preferred embodiment of the device according to the invention is characterized in that it comprises a synchronizing unit for the wire guide, comprising a lever which is responsive to the wire tension and a switching unit, operated by this lever, for controlling the movement of the wire guide, which control is superimposed on the reversal of its direction of movement.

The wire guide preferably comprises a pipe provided with a bore and arranged to be coaxially displaceable in the container, a guide for the pipe, and a drive mechanism for the traversing movement of the pipe.

Another preferred embodiment of the device according to the invention is characterized in that at least one twist stop is provided in the wire path between the spool bearing and the inner wall of the container.

As a result of the twist stop, a comparatively short twisting path is obtained which, moreover, is accurately determined with the result that the twisting process and the quality of the electrical conductor obtained are improved. It is to be noted that comparatively long twining paths are used in the textile industry.

There are many feasible embodiments of the twist stop. The twisting path can be readily varied because the pipe is journalled to be rotatable and may be blocked against rotation, a guide wheel being arranged between the spool bearing and the pipe. The pipe can preferably be made to rotate, for example, by means of a motor. If the pipe does not rotate, its lower end constitutes the twist stop; in the case of a rotating pipe, a twist effect is obtained which corresponds to a progressive increase of the twisting path as the speed of the pipe increases until the guide wheel performs the function of the twist stop, the twisting path then have a maximum length. By variation of the rotary movement of the pipe and of the twisting path in the first and/or second twist phase, the twist effect can be influenced, in

many ways.

In a final preferred embodiment of the device according to the invention, the winding mechanism comprises a screw spindle, a changing, driven carrier on which the lever with the switching device is arranged, a wire guide on the free end of the lever, and a guide for the carrier, the screw spindle being drivable by way of a reversible motor, limit switches being provided on the guide for reversing the rotary movement of the motor. In this construction, the winding mechanism and the synchronizing device are combined to form a compact unit.

The invention will be described in detail hereinafter with reference to the drawing.

FIG. 1 is a diagrammatic view of a device for forming a wire strand;

FIG. 2 is a diagrammatic view of an embodiment of the device according to the invention for twisting the wire, partly a side elevation and partly a cross-sectional view.

FIG. 3 is an enlarged side view of the winding mechanism of FIG. 2;

FIG. 4 is a plan view of a part of the device, and

FIGS. 5a, 5b and 5c are diagrammatic cross-sectional views of the pipe in various positions during the emptying of the container.

FIG. 1 shows a doubling device for assembling individual wires to form a strand, the said 'device not forming part of the present invention. Feed spools A with copper wire are rigidly mounted on a rack B. The individual copper wires C are unwound by means of flyers M and are guided over a common guide wheel E via guides N and guide rollers D. The wire strand F originating from the guide wheel E is fed, via a wheel G, to a wire guide H and is wound onto a spool K by a relative rotary and traversing movement of the wire guide H and the spool K. In the embodiment shown, the spool K is stationary, whilst the wire guide H performs both the rotary movement and the traversing movement. The wire strand F is wound onto the spool K via an arm L which is connected to the wire guide H; as a result, the wire strand is also slightly pre-twisted, so that the subsequent operations are facilitated. Y The device 1 for twisting the wire strand shown in FIG. 2 comprises an accurately balanced container 3 which is journalled to be rotatable and which is driven by an electric motor 5. The reference 7 denotes a wire guide, consisting of a pipe 9 which is coaxially arranged in the pot so as to be displaceable therein, a guide means 11 and a controllable drive mechanism for the pipe 9, i.e., a known hydropneumatic motor 13 in the embodiment shown.

The pipe 9 is provided with a central bore 15 and is rotatably mounted in an arm 19 by way of a roller bearing 17 and can be brought to rotation by a motor 21 via a belt 22; when the motor is not switched on, the pipe can freely rotate; moreover, the pipe can be blocked, for example, by means of a brake disc 23 on the shaft of the motor 21. The arm 19 furthermore accommodates a guide wheel 24. If the pipe 9 rotates at the same speed as the container 3 during the twisting of the wire, the guide wheel 24 constitutes a twist stop; when the winding pipe is blocked, the lower end 25 thereof constitutes a twist stop. The reversal of the traversing movement of the hydropneumatic motor 13 and of the pipe is achieved in known manner by means of limit switches (not shown) which control two magnetic valves in the air supply of the motor.

The device 1 furthermore comprises a bearing 27 for the rotatable journalling of a spool 29, consisting of the spool core 33 with flanges 35 and the strand package 31 accommodated thereon. In order to obtain a constant wire speed, spool 29 is driven by means of a belt 37 which is guided over two rollers 39 and 41, roller 41 being driven by a motor 43 having a variable reductor 45. The roller 39 is accommodated on the free end an increased scale in FIG. 3 and known per 'se, consists of a carrier 57 which is provided on a guide plate 59 slidably mounted by way of arms 61 and eyelets 63, on

guide bars 65. A lever 69 is arranged to be pivotable on a shaft 67 on the carrier 57. A tension spring 71 between the guide plate 59 and the rear of the lever 69 presses the latter against an abutment 73. A winding wheel 75, provided with a groove 76, is mounted on the other free end of the lever 69. Via a screw spindle 77 which is driven by the motor 53, the guide plate 59, the carrier 57 and the winding wheel 75 are driven in a reciprocating manner. The periodic reversal of the direction of rotation of the motor 53 is effected by way of limit switches (not shown) which are provided on one of the guide bars 65.

The lever 69 forms part of the synchronizing unit 81, the further elements of which are combined with the winding mechanism 51. so as to form one unit. As switching arm 85, coupled to the lever 69 by means of a carrier pin 83, is arranged to be pivotable on a shaft 87 of the carrier. Provided on a segment 89, also pivotable about the shaft 87, are a'microswitch 91 and an electromagnet 93. Also connected on the carrier 57 is a friction disc 95 which can be adjusted and which cooperates with the segment 89. The reference 97 denotes a switching bar which is shown in a plan view in FIG. 4. The switching'bar 97 is pivotable about a shaft 99 and serves to switch on the winding mechanism 51 and to reverse the movement direction of the winding pipe 9 via switches I01, 101.

The method according to the invention and the operation of the device will be described hereinafter.

Individual copper wires which are to be twisted so as to form an electrical conductor are doubled and pretwisted in advance on the device shown in FIG. 1, to form a strand, which is wound onto the spool core 33 so as to form a package 31 on spool 29. During the doubling, the end of the strand is connected to the spool core, for example, by inserting the strand end through a hole 105 in the spool core 33 and by securing it therein. In the embodiment shown, the hole 105 is provided adjacent to the flange 35 shown in the plane of the drawing. The spool 29 is subsequently mounted in the bearings 27. The switching bar 97 is manually pressed into the rest position denoted by 97 in FIG. 2.

After the container 3 has been brought to rotation, the free end of the strand F is simply lowered through the boring of the pipe 9 until it projects from the lower end thereof. As soon as the strand projecting from the pipe touches the container bottom, it will be spun against the container wall. After that, the hydropneumatic motor 13 and the motor 43 for driving the spool 29 are switched on, the spool then being driven in the direction denoted by arrow Y. Because the strand, which is fed into the container at a constant speed, is spun against the inner wall of the rotating container by centrifugal forces, the strand undergoes a twist. The traversing pipe 9 regularly distributes the wire on the container wall so as to form a package 109. The traversing movement of the pipe 9, and hence the winding pitch of the package 109, can be controlled in known manner by way of a valve in the hydraulic part of the motor 13. The driving of the spool 29 by means of the belt 37 offers the advantage that the feed rate of the strand can be simply'kept constant. By controlling the belt speed by means of the reductor 45, the feed rate of the strand and hence the twist pitch can be adjusted at a given speed of the container 3.

The broken line a in FIG. 2 denotes the path of the strand F during the feeding into the container, the broken lines b and 0 denote the strand path immediately before and after the reversal of the direction of movement, the spool 29 then having been unwound. The uninterrupted line d shows the strand during the emptying of the pot, immediately after the reversal of the direction of movement; broken line e shows the strand path when the spool is almost full again. Because the strand is secured to the spool core 33 adjacent to the flange 35 which is visible in FIG. 2, the strand passes from the front of the spool core to the rear, as denoted by the lines b, c and d in FIG. 2.

Whilst the rotary movement is uninterrupted and the direction of rotation of the spool core and of the container remains unchanged, the container is then emptied and the spool is filled; the strand then undergoes a second twist.

During the reversal of the direction of movement, the strand passing through the path c contacts the switching bar 97 and adjusts the latter to the position 97', with the result that the winding mechanism 51 is switched on via the switch 101. One of the limit switches on the guide bars ensures that the carrier 57 with the winding wheel always comes to a standstill in the same rest position, the groove 76 then being adjacent to the plane of the flange 35. During the adjustment of the switching bar 97, the strand automatically and simultaneously arrives in the groove 96 of the winding wheel 75, with the result that-the spool can be filled without interruption of the twisting process.

The twisting path can be changed by rotating the pipe 9, by letting it rotate freely or by preventing rotation of the winding pipe. In the case of a blocked, nonrotating pipe 9, the'lower end 25 of the pipe constitutes a twist stop, the twisting path then being equal to the distance between the lower end 25 of the pipe and the takeup point or take'off point P of the wire on the wall of the container 3.-

In the case of a freely rotating or motor-driven pipe, the guide wheel 24 acts as the twist stop. If the pipe 9 rotates at the same speed as the pot 3, the twisting path is substantially equal to the distance between the guide wheel 24 and the lower end 25 of the winding pipe. By changing the rotary speed of the pipe 9 by means of the controllable motor 21, an effect can be obtained which is similar to a progressive change of the twisting path. Because the guide wheel 24 is connected to the arm 19, it performs a traversing movement with the pipe 9, with the result that an adjusted twisting path remains constant. By way of the described control of the pipe, different twisting effects can be readily obtained during the filling and the emptying of the pot.

The tension in the strand is minimum both during the filling and the emptying of the pot if the strand part between the lower end 25 of the pipe 9 and the instantaneous take-up or take-off point P on the container wall is situated approximately in a plane Z perpendicular to the axis X of the container. This requirement is always satisfied during the filling of the container because the lower end 25 of the pipe always rotates synchronously with the instantaneous take-up point P of the strand. In order to prevent the strand from dragging over the package 109 on the container wall during the emptying of the container, which would increase the tension, the movement of the pipe 9 is reversed simultaneously with the reversal of the direction of movement of the strand byactuating a second switch 101', not visible in the drawing, via the switching bar 97. However, it was found in practice that, probably due inter alia to length variations by stretching of the wires, the strand tends to lag during the emptying of the container, which is to say that the take-off point P of the strand on the container wall lags with respect to the lower end 25 of the pipe 9. Such a situation is diagrammatically shown in FIG. a, the pipe 9 performing a downward movement. The synchronizing unit 81 ensures that the pipe 9 is synchronized again with the take-off point P of the strand on the container wall. The lagging of the strand causes a gradual increase of the wire tension. Under the influence of this increasing wire tension, the winding wheel 75 starts to drop. Lever 69 pivots about shaft 67 and takes along, via carrier pin 83, the switching arm 85 which pivots about the shaft 87 and which rotates, via the electromagnet 93 which serves as an abutment, the segment 89 against the frictional force exerted by the friction disc 95, After the reversal of the direction of movement of the pipe 9, the lower end 25 of the pipe 9 approaches the lagging take-off point P of the strand, with the result that the wire tension starts to decrease again. This situation is shown in FIG. 5b. Under the influence of the spring 71, the lever 69 is returned and takes along, via carrier pin 83, the switching arm 85. The electromagnet 93 is switched off, with the result that the segment 89 is held by the friction disc 95. Switching arm 85 abuts against the switch 91 mounted on the segment 89, thus operating this switch, with the result that the movement of the pipe 9 is reversed again. From this instant, the pipe 9 is synchronized again with the take-off point P of the strand, as is shown in FIG. 5c. The segment 89 is returned to its starting position by the switching arm 85 via the switch 91 which serves as an abutment.

As long as the wire tension is constant, the position of the winding wheel 75 remains unchanged. If the wire tension increases again, the synchronizing unit is actuated again. In the described embodiment, synchronisation is effected when the lower side of the pipe 9 passes through the lower half of the container 3, the electromagnet 93 not being energized at that time.

During the time that the lower end of the pipe 9 passes through the upper half of the container, the electromagnet 93 is switched on by means of a switch (not shown) on the guide 11 for the pipe 9, with the result that the segment 89 is coupled to the switching arm 85.

The described tension control by means of the synchronizing unit is particularly advantageous for the manufacture of sensitive products, where variations in the wire tension are admissible only within very narrow tolerance limits.

Instead of driving the spool 29 via the belt 37, the spool core 33 could also be directly driven; however, continuous readjustment of the speed would then be necessary, for example, by means of an electronic control system, so as to keep the strand speed and hence the twist pitch constant.

The pipe 9 could be driven by a separate motor or, via a transmission, by the motor 5.

The winding width on the spool 29 can be corrected by adjusting the said limit switches on the guide bars 65 of the winding mechanism 51.

As already explained, the twisting process can be influenced in various manners by controlling the strand speed in different phases of the process by means of the variable reductor 45 and/or by controlling the rotary movement of the pipe 9. These possibilities are further extended if the container 3 is also driven by a variable motor.

In a practical embodiment of the device according to the invention, the container which had an inner diameter of 260 mm and a height of 260 mm, was driven at a speed of 5,600 revolutions per minute by a l-hp motor; a strand composed of 40 copper wires having a diameter of 0.153 mm was twisted at a pitch of 20 mm, corresponding to 50 twists per metre, one twist being one revolution. The maximum pot filling was 40 kg, corresponding to 6,500 metres of twisted wire strand. The twisting time was 58 minutes.

What is claimed is:

1. A method of manufacturing electrical conductors, in which a number of individual metal wires are unwound from spools, are assembled to form a strand which is fed. to a twisting device, said strand being twisted while passing through the twisting device, and the electrical conductor thus obtained is wound onto a spool, comprising the steps of:

bundling a number of individual metal wires on a doubling machine to form a strand in a first process phase; winding said strand onto a spool; placing said spool in a twisting device; unwinding said strand from said spool, feeding said strand through a guide into a rotating container and depositing said strand regularly along the inner wall of the container so as to subject the strand to a first twist; and

then driving said spool so as to reverse the direction of movement of said wire strand, thereby withdrawing the strand from the container and rewinding said strand onto the same spool, while maintaining the direction of rotation of the container, so as to subject said strand to a second twist.

2. A method as claimed in claim 1, comprising additionally the steps of:

securing a beginning end of the strand to the spool prior to winding said strand onto said spool in the doubling machine; and

while unwinding said strand from said spool in the second process phase, continuing the rotation of the spool after the strand has been fully paid out so that said strand rewinds on the same spool.

3. A device for twisting a strand of wires, comprising:

means for rotatably mounting a spool on which a strand of wire has been wound for rotation about an axis of the spool;

means for driving a spool so mounted in either direction of rotation, to permit the strand to unwind from or to be rewound on the spool;

a rotatable container having an axis, for receiving the wire strand;

means for driving said container about said container axis; wire guide means defining a path for the wire strand between the spool and the container, at least a portion of said path being coaxial with said container;

traversing means for moving said wire guide means longitudinally along the container axis to distribute the strand within the container;

winding means for engaging a strand being rewound onto the spool and defining a portion of the path the strand travels so as to determine a rewinding pattern of the strand on the spool;

means for detecting when a strand, having one end thereof secured to the spool, has been completely unwound; and

means responsive to detection of complete unwinding of said strand for activating said winding mechanism to define the rewinding pattern and for reversing motion of said traversing means.

4. A device as claimed in claim 3, wherein said detecting means comprises a switch bar which is displaced by the wire strand upon completion of the unwinding, and said means for activating and reversing comprises switches actuated by motion of said switching bar.

5. A device as claimed in claim 3, comprising in addition synchronizing means for said traversing means, said synchronizing means comprising a lever whose position is responsive to tension in the wire strand during rewinding on the spool, and a switching unit responsive to a position of said lever for controlling movement of said traversing means, which control is superimposed on the reversal of motion of the traversing means.

6. A device as claimed in claim 3, comprising a guide wheel for engaging a strand being wound or unwound between the wire guide means and the winding means; and wherein said wire guide means comprises means for rotating said wire guide about the axis of said container and means for blocking rotation of said wire guide. 

1. A method of manufacturing electrical conductors, in which a number of individual metal wires are unwound from spools, are assembled to form a strand which is fed to a twisting device, said strand being twisted while passing through the twisting device, and the electrical conductor thus obtained is wound onto a spool, comprising the steps of: bundling a number of individual metal wires on a doubling machine to form a strand in a first process phase; winding said strand onto a spool; placing said spool in a twisting device; unwinding said strand from said spool, feeding said strand through a guide into a rotating container and depositing said strand regularly along the inner wall of the container so as to subject the strand to a first twist; and then driving said spool so as to reverse the direction of movement of said wire strand, thereby withdrawing the strand from the container and rewinding said sTrand onto the same spool, while maintaining the direction of rotation of the container, so as to subject said strand to a second twist.
 2. A method as claimed in claim 1, comprising additionally the steps of: securing a beginning end of the strand to the spool prior to winding said strand onto said spool in the doubling machine; and while unwinding said strand from said spool in the second process phase, continuing the rotation of the spool after the strand has been fully paid out so that said strand rewinds on the same spool.
 3. A device for twisting a strand of wires, comprising: means for rotatably mounting a spool on which a strand of wire has been wound for rotation about an axis of the spool; means for driving a spool so mounted in either direction of rotation, to permit the strand to unwind from or to be rewound on the spool; a rotatable container having an axis, for receiving the wire strand; means for driving said container about said container axis; wire guide means defining a path for the wire strand between the spool and the container, at least a portion of said path being coaxial with said container; traversing means for moving said wire guide means longitudinally along the container axis to distribute the strand within the container; winding means for engaging a strand being rewound onto the spool and defining a portion of the path the strand travels so as to determine a rewinding pattern of the strand on the spool; means for detecting when a strand, having one end thereof secured to the spool, has been completely unwound; and means responsive to detection of complete unwinding of said strand for activating said winding mechanism to define the rewinding pattern and for reversing motion of said traversing means.
 4. A device as claimed in claim 3, wherein said detecting means comprises a switch bar which is displaced by the wire strand upon completion of the unwinding, and said means for activating and reversing comprises switches actuated by motion of said switching bar.
 5. A device as claimed in claim 3, comprising in addition synchronizing means for said traversing means, said synchronizing means comprising a lever whose position is responsive to tension in the wire strand during rewinding on the spool, and a switching unit responsive to a position of said lever for controlling movement of said traversing means, which control is superimposed on the reversal of motion of the traversing means.
 6. A device as claimed in claim 3, comprising a guide wheel for engaging a strand being wound or unwound between the wire guide means and the winding means, and wherein said wire guide means comprises means for rotating said wire guide about the axis of said container, and means for blocking rotation of said wire guide. 